When a wannabe-stalker (most likely a fat,lazy nerd) decides to save time and energy on his illegal actions by just reading people's Twitter updates and imagining their situations.
the creepy man in the car in front of you turns left, then you turn left, then you're behind him on the highway for miles, and take the same exit, then end up at the same place, therefore oppositely stalking you by being in front of you instead of following you.
following the car behind you by watching their directional to see what way they will turn. makes people think they are following you. definitely entertaining when you're bored and driving around.